Telescoping ram jet construction



May 10, 1960 E. A. GALLO ET AL TELEscoPING RAM JET CONSTRUCTION 2 Sheets-Sheet 1 Filed July 19, 1957 May 10, 1960 E. A. GALLO ET AL TELESCOPING RAM JET CONSTRUCTION Filed July 19, 1957 2 Sheets-Sheet 2y INVENTORS, .Elia A Gallcl BY Donald E'Llar'k Ed'warcf W Schwan-12 A s ell may be lired'is decreasediwith'an increase of muzi States,

TELEscoPING RAM JET CONSTRUCTION Y by the Secretary of the Armyv y L- Application July 19, 1957, senin N0. 614,549 1 5 claims. A(ci. 1oz-49) 'This inventionrelates to gun launched, spin stabilized, l5 ram jet` powered projectiles and particularly to suchY projectiles having a` telescoping construction. l

Since the advent of high altitude high speed bombers ithas been found increasingly difficult to produce a kill with present anti-aircraft guns andpr'ojectiles. One ref'A 20 sult is that offensive aircraft have a greater latitude of bombing altitudes. If anti-*aircraft .projectiles and guns ca n. .be made more accurate, offensive aircraft will .be forced to operate at higher altitudes to prevent unreas onable losses, and thereby reduce the yaltitude range over which guided missiles must operate.

. To increase the effectiveness of an anti-aircraft gun the timeof ight to the target must be'reduced.

Modern anti-aircraft computers predict the future position nof a target by observation ofthe course and speed of. the target over theimniediate past and the assumpv tionv is made that the target will maintain this course and speedfor the interval required for -the projectile to reach the target. Since modern high speed bombers are withinV range for approximately 20 seconds, at altitudes in the 35 vicinity of 40,000 feet, and since it takes a present day V high velocity shellV 12 to 20 seconds to reach such an altitude, it is obvious that the time of flight to target must be shortened if anti-aircraft fire is to be electve. Though time of flight may be shortened by increasing 40 muzzle velocity of the gun, any increase in muzzle 'city vresults -in increased gun weightand decreased ility. It also 'results in greater wear on the gun bar-V iid produces muzzle yawon the projectile Vwhich de'- as'esaccuracy. vFurther the rapidity with' which the 45 By the, use of a ram jet projectile,a two fold advantage -However to produce a rapid fire ram jet projectilethe length of a round must beheld .to a minimum. I Round lengthis a function ofihigh rate of firing since gun loaders are normally limited to a total value of round lengthl per v unit time.' If ka high rate of ring is to be obtained it isk 55 mandatory that the length of each round be held vtofa minimum. self-propelledprojectile having a combustion charitbery will ordinarily be Ofgreaterlength thanf'the usualr projectile. Therefore it is necessary to provide a -pro' 50 jectile ofthe ram jettype with a telescoping feature to pnovidea round having a minimum length while being handled and-loaded for iii-ing, and which is automatically extended to operating position after having been launched forilight..

-A' further advantage of thetelescoping feature of a ram ljet projectile is 'that thev combustion chamber is sealed from the propelling gases while traversinga gun barrel, which results in a lighter weight combustion chamber con-V struction. Ina non-telescoping ram jet the gas pressure generated'by the propelling charge is equal, within and without the combustion chamber whilestheprojectile fis l along lines 2-2 thereof.. Le

' inthe gun b arrel.q Asthe projectile 'leaves the rel the pressure; on the outside ofthe combustion charm ber rapidly diminishes to atmospheric pressure, while the pressure within the chamber remains substantially equal to propelling pressure. As a result a non-tele'scoping combustion chamber must withstand a high pressure differential Whereas in a telescoping projectile .the combustion chamber can be of light weight construction since its -in-v terior is sealed fromjthe propelling gases.

The projectile `of this invention overcomes the above enumerated disadvantages of prior anti-aircraft projectiles; accomplishes the two fold improvement in antiaircraft defense set .out above, and is suitable for use in rapid lire guns, and isof minimum Weight.

The unique ydesign of this projectile allows the centerbody portionof the projectile -to be telescoped within the combustion Achamber, when the combustion chamber isjnot in use. The centerbody portion houses thev fuze, warhead, and fuel tank as well as the fuel metering valves andignition means as'willbe more fullydescribedhereinafter.H When iired the combustion chamber shell is pushed to the rearby aerodynamic forces to expand the projectile to operatingposition.

AThe air inlets fo the ram j et engine may bein. the

form of. front,' opening air diffuser or of side opening air scoops. When the front opening diiuser is used the projectile of this invention is slightly longer than theiprojectilewith side opening inlets. As a result the side opening inlets mayfbe preferred to allow each gun of a battery to fire the maximum number of rounds per unit time.

In the side inlet construction the ai-r scoops are rel tracted within the combustion chamber adjacent thecen-v terbody in telescoped position. When the projectile is extended the `air scoops are thrown out through openings in the forwardend ofthe combustion chartber'V shellby centrifugal force. f Fuel 4pumping accomplished by centrifugal force lacting on, the fuel in the tank due to rotation of the projectile.

In the front opening diffuser arrangement the fuel is discharged through nozzles, located in streamlined struts supporting the diffuser in spaced relation with thecen; terbody. With'the side inlet arrangement the fuel 'is sprayedinto the air passages formed between the air scoops and eenterbody by a fuel metering valve whichis the subject;y of aseparate application -by Howard D. Hotfman, Ser. N o. 526,341, iiled Aug. 3, 1955.

Therefore one object of this invention istofprovidea gun tired ram jet projectile. j 'Anotherobject is to v'provide a ram jet propelledguii tired projectile of minimum weight which'is suitable'for rapid' loading and tiring. Another Aobject of this invention is Ato providea ram jet, gnv tired, telesco'laing"` projeile` which is automatically extended to opeftiugpos flight. Y,

ention' 'is to pr vide atwo piece rain 'jet powered projectile' in whtchlsleenter'bay portion, having a fuze, warhead, fuel ltank,-fu el mete r.

ing. and ignition devicestherein, is riormall-yf.telescopeil.

within a lcombustion chamberand extended to operating position after launching. Y

VFor ya more complete understanding ofv the- Vspecific nature of this invention, as well as other objects andack viantages,y reference may be had to thefaccompanying drawings illustrating a preferred embodiment whereimlike 4 characters refer yto like parts throughout:andin-whichzgj.

Fig. 1 s a longitudinal Asectional view showing theprof jectile in tiring or closed position. f f

Fig. 2 is a cross sectional view,V of theprojectileof. .igl

2,935,946 Patented May 10,1960

Fig. 3 is a longitudinal sectional view showing the projectile in expanded or operating position.

Fig. 4 is a front elevation showing the air scoops in their opened position during flight.

'Fig'. v5 is a plan view of one of the flame holders taken along a plane indicated by lines' 5 5 of Fig l.

Fig. 6 is a partial cross sectional view ofia front opening air diffuser type projectile.

As shown in Figs. 1 and 3 the projectile 1 comprises a centerbody 2 telescopically associated with the combuSr tion chamber shell 4. Fig. l shows the projectile closed, or in loading and ring position, wherein the centerbody 2 occupies the combustion chamber 3v of shell 4, with the air scoops 12 in retracted position. The expanded or operating position of the centerbody isA shown in Fig; 3.

The centerbody 2 is of a generally tear drop configuration having an ogive nose portion formed with a fuze 7, attached in the usual manner, and a high explo'- sive chamber 6 to the rear of the fuze. The rear portion of the centerbody forms a fuel tank 5 sealed and separated from the explosive chamber 6 by an archedv internal wall 5a. The downstream portion of' the centerbody tapers rearwardly to an igniter squib 8. Forwardly of the squib 8 is annular shoulder 2a formed integral with the centerbody.

' The shoulder 2a, best shown in Figs. 1 and 3, coacts with the forward converging portion, ofthe nozzle 16 to provide a seal which prevents the escape" of propelling gases past the centerbody to atmosphere through the front of the shell 4 and the gun barrel. If desired centlifllgally operated locking pins (not shown) may be provided in the forward portion of the exhaust nozzle to engage that portion of the centerbody between the shoulder 2a and the squib 8. However set back forces on the heavy centerbody should be sufficient to make thisseal.

As shown inv Figs. l and 3 fuel metering valves 9 are provided for each air scoop 12. The valves are placed inthe centerbody so as to communicate the fuel tank 5 with air passages 12a formed between the air scoop 12 and the tapered rear end of the centerbody?. Since the inlet air scoops 12 are situated directly over the fuel valves 9 the fuel not carried downstream bythe air will be directed to the combustion chamber 3 by the channelled underside of scoops 12. The fuel valves 9 operate to meter the fuel from the tank 5.when pressurized by centrifugal forces, due to projectile. spin. As previously stated the fuel valve is the subject matter of the copending application noted above.

As best shown in Fig. 2 the lair scoops 12 are pivotly mounted on pins 11 recessed into a series of built up bifurcated ridges, or lugs 10, formed integrally with the centerbody housing. The radi-al outward surface of the lugs are longitudinally splined and grooved as at 13 to mesh. with corresponding grooves and splines 14 formedinternally of shell 4, thus preventing relative rotation between centerbody 2 and combustion chamber shell 4.v

Flame holders 15 `are provided in the downstream end of air passages 12a to the rear of -air scoops 12and forwardly of the annular shoulder 2a. v

x Igniter squib 8, formed integral with the centerbody, is held within the diverging portion of the nozzle 16 in the firing position shown in Fig. l to expose an igniter powder grain (not shown) to the launchingVV gases. Once red by the launching gases from the customary cartridge case the igniter grain continues to burn providing the igneous element for the fuel-air-mixture entering the cornbustion chamber when the projectile is expanded as shown in- Fig. 3.

As best seen in Fig. 3 the combustion chamber shell 4 has internally longitudinally splined sections 14: separated by air scoop guided recesses 12b. The splined sections 14 run substantially the length of the combustion chamber 3 terminating a short distance forwardly of the nozzle 16' formed integrally with shell 4 at the exhaust end of chamber 3. At the forward end of shell 4 is an nularly raised portion forming stops 4a which prevent the centerbody 2 separating from shell 4. The scoop guide recesses 12b extend forwardly of the opening v18 as well as Irearwardly therefrom. The portion 20 of the centerbody 2 adjacent the scoop guides 12b is also recessed by the omission of splines to provide an air passage between `the centerbody 2 and the shell 4 when the centerbody-is in the firing position as shown in Fig. l. This air passage provides air llow to the forward annular face 16a of thev exhaust nozzle to apply a force to the shell 4 which will extend the projectile by pushing the shell rearwardly. These opening air passages become substantially cut off when the shell 4 is displaced to cause abutment of stop 4a and centerbody portion 20 due to the raised portion of the stop.

The automatic extention of the projectile is accomplished in the following manner.

When the shell clears the gun barrel a considerable ram pressure will be generated which will act' Vover the entire surface of the inner portion of the shell 4. This ram pressure will also act on the up-stream face 16a of the exhaust nozzle Whilethe downstream end of the'exhaust nozzle will encounter low pressure as a. result of base drag of the projectile. The drag on the outer surface of shell 4 will bev appreciably larger than theone on the inner portion,.or over'the centerbodyV when the shell 4 rst moves opening the seal between shoulder'Za and' the exhaust nozzle 16 since air ow will be much greater over the outside of shell 4 than between shell 4 and centerbody 2. Also aiding in the extension ofthe projectile is the fact that the inertia of the centerbody is far greater, due to theV weight differential between the shell 4 and centerbody 2, than the inertia of shell. A further aid in opening the projectile fully will be the escape of fuel tothe partially `opened combustion charnber as the fuel will be metered by valves 9 as soon as the projectile reaches its operating angular velocity or'leaves the gun barrel.

When the projectile is fully extended the centerbody 2 rests against stops 4a and the scoops 12 are aligned with the slots 18 in the shell 4. The scoops 12 being extended through the slots due to centrifugal force due to projectile spin.

The centerbody is slidably mounted in the shell 4 and relative rotation prevented by the splines and grooves 14 mating with the splines and grooves machined` in the lugs 10 as shown in Fig. 2. Centerbody 2 is further splined at 20, which is approximately at the center of gravity of the centerbody. The splines of the centerbody portion 20 ride in the grooves of section 14 of shell 4 to transmit torque from the rotating bands 17 to the centerbody 2.

Shell 4 is also provided with a bourrelet 19 on the outer periphery at approximately the center of gravity of the collapsed projectile. Y

Fig. 6 shows a modiiication of a ram jet projectile in which the centerbody 2 is surrounded by-a front opening air diffuser 21. The centerbody of this projectile contains the fuze 7 explosive chamber 6, fuel tank 5, and

igniter 8. Surrounding the centerbody is annular air passage formed by a cylindrical outer section 21v and centerbody 2. Fuel pumping is accomplished by centrifugal force on the fuel spinning in the tank 5. The fuel being discharged through nozzles (not shown) located in struts 22 supporting the cylindrical outer section 21.

The modified projectile of Fig. 6 is opened. by aerodynamic pressure developed in the annularV air inlet 21a acting on the upstream face of the nozzle of the shelly 4 as previously described in connection with the sideopening air scoop design shown. in Figs. l and 3.

In view of the foregoing the operation of theV device will be self evident to those skilled'in the art. And while a. preferred embodiment has been shown and described various modifications Will become apparent in. the light of the foregoing disclosure without departing from 'the ,l i spirit and scope of the invention as set forth vv .pended claims. j i 'Weclaim;` j `l v 1. In a spin Astabilizedfram-jet projectile, a cylindrical' inthe apinternallysplined combustion chamber shell havingfa v venturi nozzle the aft end thereof, a centerbody having V a series" of spaced, y radially extending, bifurcated lugs v,splinedalong their outer ends and adapted to mesh with said internal splines in said shell, said centerbody being telescopicallymounted -within said shell for linear movement alon'g the::longitudinal axis thereof and' normally Y held'r against angularmovement'relative to said shell by said splines in said shell and on said lugs, said centerbody normally telescoped within said shell 4and adapted to slide forwardly intoan` operating position by raerodynamic forces during free llight thereofga combustion chamber formed within said shell when said-centerbody is in said operating position, a fuel tank and warhead housed within said centerbody, retractable ram air `scoops Vpivotally f mounted in said "bifurcated lugs on said centerbody, ignis f tion means integral with jthe rear endY of said centerbody projecting intojsaid combustion chamber, and means to inject fuel underf'p'ressure into said ram air inlets in yextended position. i Y,

v 2. In a ram-jet projectile, 'a generally `tear drop shaped rearwardly into said combustion chamber of said shell, a plurality'of air scoops pivoting upon the rearward portion ofthe outer peripheral surface o f said centerbody and in longitudinal alignment witha series of slots in the rforward portion of said shell, said air scoops normally "held in closed position by the'wallfof said shell Awhenvsaid ram-jetv construction is in collapsed position Vanddesigned l to Yenter said `slots and assure an open position upon extension of said projectilebody in said shellfto'supply a Y' f flj-iiow oflairto said combustion chamber in "said shell, and aplu'rality of valves piercing said fuel tank t supply fuel into thearl passage formed byrsaid scoops. Y

3'. Ina ram-jet projectile, as claimed in claim 2, wherein means for Ypivoting said' air, scoopsupon said centerf body comprise aseries of `rearwardlyextending bifurcate lugs'- integral with and disposed lrearwardly onathe outer peripheral surface of said centerbody, aipivot mounting one of said air scoops in each of said bifurcations for rotation therein.

4.1m afspin stabilized telescopijng ram-jet projectile,V a cylindrical combustion chamber shell having a venturi nozzle at its rearward endand a'plurality of circumferentially4 disposed openings adjacent its forward end,

y,centerbody including a fuze, a warhead, a fuel tankand l vanaigniter,v a tubular Yshell including a combustion-chamber and arearwardly disposed integral venturi nozzle, 1 said shell adapted to receive said centerbody in telescoping 'relation therein, one or more valves piercing said fuel .tank of said centerbody to supplyl fuel fromrsaid tank 6 Y peripheral Wall of said shell extending substantially the longitudinal length thereof, a generally tear drop, shaped centerbody telescopically received within said,shell,said centerbody having splined and groovedr areas formed 'oni' 5" its outer periphery `cooperating with said-l splines antl'jV`V grooves in' said shell to guide said centerbody.longitudi-v nally Within said shell and transmit torque from driving are held in their opened positions, and said scoops normally overlying a plurality of fuel metering valves communicating said fuel tank vwith an air passage formed by said air scoops and said centerbody, anY ignition squib.A

integral with the centerbody and located downstream'of said valves, means to seal the rear end'of saidc'ombustion chamber from launching gases when saidfcenterbody is telescoped within said shell including 4annular shoulder formed integrally .with` said centerbodyiabutting ,theupY-j stream face of said nozzle, ram air passagemeans formedv by recesses on the outer periphery of said centerbody and". j inner wall of said shell, said air passage conducting ram air to the upstream face of said nozzle toinitiallymoveV said shell rearwardly, said ram air passage'means being shut olf when said centerbody engages a built upja'nnular I c stop at the forward end of said shell.

5. In a spin-stabilized ram-jet projectile, a tubular shell defining a stop member at its forward end thereof, aVY

generally tubular air diffuser having a diameter substanti-ally less than the diameter V.of said shell telescopically mounted within said shell, the forward movement of said air diffuser being limited by-said stop member ony said;

shell to prevent separation therefrom, a series of spaced struts carried by the inner peripheral surface of said shell,

and a generally cylindrical centerbody having a diameter f substantially less than the diameterrof/,sad air diffuser,

therebeing splined and grooved areasfformed on the inner y..

fixed to said struts whereby 4there is ariaannularspace between said air diffuser and said centerbody,"said air ,Y v

diffuser and said centerbody moving as a unit toa fully extended position by aerodynamic pressure developed in said annular space.

References Cited in the file of this patentl ,Y

UNITED STATES PATENTS Y Billman July 7, 1953 Cumming Jan. 125, 1955 lFOREIGN PATENTS 438,029

- Banning- May 16, 1950 l France lViayr24,191 Sl 

